Endersending
Experienced Member
I am currently working on an IMSAI 8080 System with a Cromemco ZPU and 32K of static ram.
I purchased a Cromemco 4FDC with Rdos 1 on it. I have been able to access the serial console and use rdos but that is about as far as I can go. My next step is to boot CDOS with 8" floppies but I have hit multiple roadblocks. I do not currently have a CP/M or CDOS formatted disk. Rdos 1 cannot format disks. I am also learning that both my 8" drives need to be fixed/realigned. The first drive will read and write until about track 25 and starts not reading/writing correctly. The other is not responding correctly to head steps and head loading.
I have been using ImageDisk head alignment and trying to write 8" floppy images. This setup is being done with a 286 PC and a 34 to 50 pin adapter that I bought online. So I am currently at a chicken and egg problem. I cannot format a disk. I can't aligned my drives because I have no formatted disks. I have watched a Curius Marc video where they use an oscilloscope to align the heads with an alignment disk. I bought some 8" floppies with CP/M software which I figure will work to use with an oscilloscope and ImageDisk to aligned it properly.
I have also learned that none of my floppy controllers can write 128 byte sectors verified by ImageDisk's TESTFDC program. I am guessing I need a controller that will do 128 byte sector writes to create a proper disk. I have ordered a AHA-1542B scsi controller with onboard floppy controller that is listed as working with 128byte sectors. I guess I need to wait until that arrives with some formatted CP/M disks.
I have been reading through the Glitch works tutorial on transfering CDOS over serial. This doesn't work with rdos 1. I keep getting a com timeout error trying to transfer the image. So my questions will start with rdos 1 and should I burn a new 2708 eeprom with rdos 2.52?
Since I am using a Cromemco 4FDC and I also ordered a TUART board for serial, I figure my best path is to use CDOS as the operating system for this machine. Is this a wise choice?
Once the machine is running with an OS and I can always try different CP/Ms.
Advice on moving forward would be great. I have my 8" floppy drives (single sided, single density, soft sector) I would like to use, although I might start with 5.25 360K floppies. I have been confused with which floppy drives I should be using. Most of the CP/M images I have found will say 8" or 5" but not density. Like I have said I am using ImageDisk and I am not sure if the images I am writing are the correct density. Here is a link to Dave's Old Computers where I am planning on using the Cromemco Rdos package to boot the system. In the zip file there are two disk images, but I am unsure of the density. Should I be using double density 8" drives? Can the 4FDC mix density and size floppies? can I run 2 a single density 8" with 2 doulble density 5.25" drives? From the way I understand it, the controller supports one size or the other, not both at the same time. Please correct me if I am wrong.
It is looking like this will be an IMSAI case with Cromemco Guts and software. Any advice to the above ramblings would be greatly appreciated.
I will post back as soon as the floppy controller and formatted disks show up and I can get some floppy drives writing disks with ImageDisk.
Thank you for the VCF Site. iI's great to have a connection to people with knowledge about this stuff.
I purchased a Cromemco 4FDC with Rdos 1 on it. I have been able to access the serial console and use rdos but that is about as far as I can go. My next step is to boot CDOS with 8" floppies but I have hit multiple roadblocks. I do not currently have a CP/M or CDOS formatted disk. Rdos 1 cannot format disks. I am also learning that both my 8" drives need to be fixed/realigned. The first drive will read and write until about track 25 and starts not reading/writing correctly. The other is not responding correctly to head steps and head loading.
I have been using ImageDisk head alignment and trying to write 8" floppy images. This setup is being done with a 286 PC and a 34 to 50 pin adapter that I bought online. So I am currently at a chicken and egg problem. I cannot format a disk. I can't aligned my drives because I have no formatted disks. I have watched a Curius Marc video where they use an oscilloscope to align the heads with an alignment disk. I bought some 8" floppies with CP/M software which I figure will work to use with an oscilloscope and ImageDisk to aligned it properly.
I have also learned that none of my floppy controllers can write 128 byte sectors verified by ImageDisk's TESTFDC program. I am guessing I need a controller that will do 128 byte sector writes to create a proper disk. I have ordered a AHA-1542B scsi controller with onboard floppy controller that is listed as working with 128byte sectors. I guess I need to wait until that arrives with some formatted CP/M disks.
I have been reading through the Glitch works tutorial on transfering CDOS over serial. This doesn't work with rdos 1. I keep getting a com timeout error trying to transfer the image. So my questions will start with rdos 1 and should I burn a new 2708 eeprom with rdos 2.52?
Since I am using a Cromemco 4FDC and I also ordered a TUART board for serial, I figure my best path is to use CDOS as the operating system for this machine. Is this a wise choice?
Once the machine is running with an OS and I can always try different CP/Ms.
Advice on moving forward would be great. I have my 8" floppy drives (single sided, single density, soft sector) I would like to use, although I might start with 5.25 360K floppies. I have been confused with which floppy drives I should be using. Most of the CP/M images I have found will say 8" or 5" but not density. Like I have said I am using ImageDisk and I am not sure if the images I am writing are the correct density. Here is a link to Dave's Old Computers where I am planning on using the Cromemco Rdos package to boot the system. In the zip file there are two disk images, but I am unsure of the density. Should I be using double density 8" drives? Can the 4FDC mix density and size floppies? can I run 2 a single density 8" with 2 doulble density 5.25" drives? From the way I understand it, the controller supports one size or the other, not both at the same time. Please correct me if I am wrong.
It is looking like this will be an IMSAI case with Cromemco Guts and software. Any advice to the above ramblings would be greatly appreciated.
I will post back as soon as the floppy controller and formatted disks show up and I can get some floppy drives writing disks with ImageDisk.
Thank you for the VCF Site. iI's great to have a connection to people with knowledge about this stuff.